Probing axion mediated fermion–fermion interaction by means of entanglement

Abstract

We propose a new approach in the investigation and detection of axion and axion-like particles based on the study of the entanglement for two interacting fermions. We study a system made of two identical fermions with spin −1/2, and we show that fermion-fermion interaction mediated by axions leads to a non-zero entanglement between the fermions. An entanglement measurement can reveal the interaction, providing an indirect evidence of the existence of axions. We discuss how the other interactions affect the entanglement, and how to isolate the axion contribution. Particular care is devoted to the analysis of the magnetic dipole-dipole interaction, which turns out to be the most relevant source of noise in our approach and we show that it can be suppressed by setting opportunely the duration of the observation. We also introduce a two-body correlation function, which could be directly observed in an experiment, and plays the role of an entanglement witness.

Neutron interferometry, fifth force and axion like particles

“…( 2) corresponds to a long-range spin-dependent force among the neutrons. Therefore our analysis well fits within the context of fifth force experiments [33][34][35][36]45,46]. In the following we shall assume that the neutron velocities are non-relativistic and analyze the interaction Hamiltonian (2) within the context of ordinary quantum mechanics.…”

“…The results presented in the figure are in the spirit of a model-independent analysis, which in principle applies to any ALP which experiences an interaction with neutrons. Since masses and couplings vary sensibly Notice that the current laboratory constraints on g a N N from fifth force experiments [33][34][35][36]45,46] set an upper bound of the order ∼ 10 −4 . Our setup could in principle improve on such bound.…”

“…The latter yields an effective fermionfermion interaction [31,32] in which the ALP plays the role of a mediating boson. For this reason, the detection of ALPs is naturally tied not only to electrodynamics but also to the possibility of experimentally probing interactions between fermions [33][34][35][36]. On the other hand, in the context of neutron physics, interferometry has proven to be a formidable tool in investigating particle interactions and their quantum properties.…”

Geometric phase of neutrinos: Differences between Dirac and Majorana neutrinos

“…This argument is independent of whether the two Hamiltonians H (1) and H (2) produce distinct observable effects or not. We remark, however, that while the standard oscillation formulae are not affected by the Majorana phase α [3], the latter may well show up in other circumstances, for instance in the propagation in a dissipative medium [4,5] for which the oscillation formulas depend on the Majorana phase. Finally, it is not at all clear why the charged lepton field rephasing should have any effect on neutrinos, which should not be affected by the latter, because then it is obvious that any quantity depending only on the neutrino oscillatory evolution suffers no modification from the charged lepton field rephasing.…”

Cosmological Spectrum of Two-Point Correlation Function from Vacuum Fluctuation of Stringy Axion Field in De Sitter Space: A Study of the Role of Quantum Entanglement

“…Here we want to point to a few works, refs. [25,26], where the authors have studied quantum field theory of axion fields and its relation with quantum entanglement.…”